A mass flow controller (MFC) is a device used to measure and control the flow of liquids and gases. Generally, a MFC is designed and calibrated to control a specific type of liquid or gas at a particular range of flow rates. The MFC can be given a setpoint from 0 to 100% of its full scale range but is typically operated in the 10 to 90% of full scale where the best accuracy is achieved. The device will then control the rate of flow to the given setpoint.
MFCs are used pervasively in the semi-conductor manufacturing to implement product-specific recipes involving different gases required at desired flow-rate set-points. Thus, MFC performance is crucial for overall process yield maximization. An integral part of the mass flow controller is the valve, which regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways.